<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .wrapper {
            background-color: #3a8ee6;
            height: 200px;
            display: flex;
            flex-flow: row-reverse wrap;
        }

        .flex1 {
            background-color: #5daf34;
            width: 400px;
        }

        .flex2 {
            background-color: #666666;
            width: 400px;
        }

        .flex3 {
            background-color: #e76f6f;
            width: 400px;
        }
    </style>
</head>
<body>
<div class="wrapper">
    <div class="flex1">盒子1</div>
    <div class="flex2">盒子2</div>
    <div class="flex3">盒子3</div>
    <div class="flex3">盒子4</div>
    <div class="flex3">盒子5</div>
    <div class="flex3">盒子6</div>
    <div class="flex3">盒子7</div>
    <div class="flex3">盒子8</div>

</div>

</body>
</html>